The AVM system captures the surrounding environment through cameras which are provided at a front side, a rear side, a left side, and a right side of the vehicle, composes the captured images, and compensates for an overlapping area to be naturally displayed to display the surrounding environment of the vehicle on a screen in a bird's eye view manner. Therefore, a driver may accurately recognize surrounding circumstances of the vehicle while viewing the displayed surrounding environment and conveniently park without depending on an image which is reflected on a side mirror or a rear view mirror.
In such an AVM system, a mounting position of the camera in the vehicle and a directivity of the camera are designated to capture an image and a specification of the camera is designed in advance so that errors between four cameras which are mounted at front, rear, left, and right sides of the vehicle may be compensated by a tolerance compensating program in a product line.
A main purpose of the tolerance compensation is to minimize an installation tolerance error of a camera. A positional relationship between cameras may be changed due to deterioration of a vehicle, a weight change of the vehicle caused by the number of passengers, a change of tire pressures, or an impact by an accident. Therefore, as illustrated in FIG. 1, an inconsistent area may be generated at a boundary between images generated by the cameras or an inconsistent area with an actual ground may be generated in an entire AVM monitor image.
A typical image which is output through the AVM system has a virtual point of view which is viewed from the top of the vehicle so that a straight parking line corresponding to a parking space needs to have an exact straight line shape not only in an image for one channel, but also in a composite image for all channels.
However, it can be seen that a disconnected portion (a circle represented with a dotted line) is found at a part of a left parking line of the vehicle in FIG. 1. Further, the parking space configured by parking lines needs to have a shape exactly complying with a standard (for example, a rectangle) of the parking space. In this case, when parking lines coexist at a boundary between images generated by the cameras, extending lines of the parking lines need to exactly meet at one point and a difference of the portions between channels which do not match may be determined as a tolerance.
The inconsistency of the boundaries between channels deteriorates a subjective image quality for a driver viewing the image and cannot provide exact information on surroundings of the vehicle to the driver so that a driver assistance function which is considered as an essence of the AVM system may be unhelpful.
In order to solve the above-mentioned problems, there is a method that manually compensates for the tolerance using a tolerance compensating line which is provided in a product line or an A/S center, but the method has a limitation that requires a separate time and effort of a driver and requires excessive cost.